POS0984 PREVALENCE OF axSpA IN PATIENTS TREATED FOR CHRONIC BACK PAIN IN CHIROPRACTIC CLINICS: THE OREGON CHIROPRACTIC AXIAL SPONDYLOARTHRITIS STUDY (ORCAS) – AN INTERIM ANALYSIS
Authors: S. Kiwalkar, S. Bhalerao, K. Phung Nguyen, R. Quinn, D. Perham, W. Malatestinic, R. Bolce, T. Hunter, P. Khurana, A. Deodhar
Journal: Annals of the Rheumatic Diseases (2022)

Background Non-rheumatology settings such as chiropractor clinics, where chronic back pain (CBP; including chronic back, buttock, or hip pain) patients are first seen, lack consistency in referral of patients to rheumatologists where the underlying cause may be axial spondyloarthritis (axSpA). Objectives Primary objective was to estimate the prevalence of axSpA in CBP patients attending four chiropractic clinics in Portland, Oregon, referred to a rheumatology clinic using a referral strategy identifying features of spondyloarthritis (SpA). Methods Adults attending one of four chiropractor clinics between Nov 2020 and Nov 2021 for CBP starting before age of 45, without prior diagnosis of SpA were eligible for inclusion. Patients were referred to rheumatologist for diagnostic assessment via phone consultation, if they had inflammatory back pain (IBP) and/or ≥1 of the following features: a family history of SpA, inflammatory bowel disease (IBD), psoriasis, good response to non-steroidal anti-inflammatory drugs, history of heel pain, uveitis, or joint swelling. The subsequent rheumatology assessment included history, C-reactive protein, HLA-B27, x-ray and MRI of the sacroiliac joints. Based on the assessment, patients were categorized as radiographic axSpA, non-radiographic axSpA, peripheral SpA, or no SpA. Endpoints were summarized using descriptive statistics. Results A total of 3,103 visits were recorded at four chiropractic offices between Nov 2020 and Nov 2021. Top ten chief complaints are presented in Figure 1. In total, 115 patients were referred by the chiropractors and 84 patients were confirmed to be eligible. Of the 74 patients who provided consent, 59 (79.7%) had IBP, and 66 (89.2%) had at least one clinical SpA feature. At interim data lock, 63 patients were fully assessed by a rheumatologist, of which 7 (11.1%) were HLA-B27 positive and 24 (38.1%) had rheumatologist-evaluated IBP. Eight (12.7%) patients had SpA, 6 (9.5%) were diagnosed as axSpA and fulfilled Assessment of Spondyloarthritis International Society (ASAS) classification criteria, 1 (1.6%) patient was diagnosed as psoriatic arthritis without imaging evidence of axial involvement and fulfilled Classification Criteria for Psoriatic Arthritis, and 1 (1.6%) had undifferentiated peripheral SpA and fulfilled ASAS Classification Criteria. Figure 1. Chief complaints reported by patients at chiropractor visits (n=3103) Conclusion More than 10% of patients attending chiropractic clinics for musculoskeletal complaints had undiagnosed SpA conditions, with axSpA being the most common. Educational efforts targeted at chiropractors to suspect and refer appropriate cases to rheumatologists are needed. Table 1. Demographic and clinical characteristics stratified by diagnosis as confirmed by Rheumatologist Radiographic axSpA (N = 1 ) Non-radiographic axSpA (N = 5 ) Peripheral SpA Including PsA (N= 2 ) No SpA (N = 55 ) Age, years (Mean; SD) 73 (-) 36.8 (6.4) 46 (1.4) 45.1 (12.1) Sex, Female – n (%) 0 4 (80.0) 2 (100) 32 (58.2) Family history of spondyloarthritis, Yes – n (%) 0 1 (20.0) 1 (50.0) 9 (16.4) Chronic back pain duration, years (Mean; SD) 49 (-) 12.4 (6.0) 11 (7.0) 15 (10.8) Confirmed during rheumatology visit – n (%) IBP* (4 out of 5 criteria as checked by patient) 1 (100) 3 (60.0) 1 (50.0) 27 (49.1) IBP* (4 out of 5 criteria per rheumatologist’s opinion) 0 2 (40.0) 0 22 (40.0) History of plantar fasciitis or Achilles tendinitis 0 4 (80.0) 2 (100) 14 (25.5) History of peripheral joint swelling 0 0 1 (50.0) 8 (14.6) Positive response to NSAIDs 1 (100) 1 (20.0) 2 (100) 21 (38.2) Psoriasis 1 (100) 0 1 (50.0) 2 (3.6) Inflammatory bowel disease 0 0 0 1 (1.9) Uveitis 0 0 0 1 (1.8) HLA-B27 positive 0 2 (40.0) 1 (50.0) 4 (7.3) CRP, Above 10.0 mg/L 0 2 (40.0) 1 (50.0) 1 (1.8) SI Joints X-ray positive for sacroiliitis (modified New York criteria) 1 (100) 0 0 1 (1.8) SI Joints MRI positive for active inflammation 1 (100) 3 (60.0) 0 0 *According to the Assessment of SpondyloArthritis international Society (ASAS) classification criteria for axSpA Disclosure of Interests Sonam Kiwalkar: None declared, Shireesh Bhalerao Consultant of: Eli Lilly and Company, Kim Phung Nguyen: None declared, Rose Quinn: None declared, Dave Perham: None declared, William Malatestinic Shareholder of: Eli Lilly and Company, Employee of: Eli Lilly and Company, Rebecca Bolce Shareholder of: Eli Lilly and Company, Employee of: Eli Lilly and Company, Theresa Hunter Employee of: Eli Lilly and Company, Pragya Khurana Consultant of: Eli Lilly and Company; ICON plc has received funding from several pharmaceutical companies involved in the marketing products for treatment of spondyloarthritis., Atul Deodhar Speakers bureau: Janssen, Novartis, Pfizer, UCB, Consultant of: AbbVie, Amgen, Aurinia, Bristol Myers Squibb, Celgene, Eli Lilly, Glaxo Smith &amp; Kline, Janssen, MoonLake, Novartis, Pfizer, UCB, Grant/research support from: AbbVie, Bristol Myers Squibb, Celgene, Eli Lilly, Glaxo Smith &amp; Kline, Novartis, Pfizer, UCB